Battery state estimation (BSE) is a primary function of a battery management system of an electrified vehicle (EV). Two major functions of BSE are state of charge (SOC) estimation and state of power (SOP) estimation. SOC represents a current amount (e.g., a percentage) of a charge capacity that is currently being stored by the battery system. SOP represents a peak power capability of the EV. An accurate SOP estimation is important for determining maximum charging/discharging power of the battery system for an arbitrary time interval, particularly for EV applications.
Conventional SOP estimation techniques (SOC limited, voltage limited ohmic resistance (VLOR) only, voltage limited first-order extrapolation of open-circuit voltage (VLEO) with resistor-capacitor (RC) dynamics, etc.) do not consider variations of all resistor and capacitor values during a constant current pulse, particularly over long time intervals. Because RC parameters are a function of SOC, the RC parameters could potentially vary greatly during the current pulse. Thus, while such battery management or BSE systems work for their intended purpose, there remains a need for improvement in the relevant art.